We can have an object hierarchy in a geographic plane; that is some objects may be linked to other objects by position, while others may be independent and fixed in position. We need object data, and information on composing it. Composing means locating it in reference to other objects in time as well as space. Once the object is rendered (rendering here means display of multimedia object on screen) the author can manipulate it and change it's rendering information must be available at the same time for display.
If there are no limits on network bandwidth and server performance, it would be possible to assemble all required components on queue at the right time to be rendered. In Addition to the multi-user composing function, a multi user authoring system must provide resource allocation and scheduling of multimedia objects. This gives raise to a number of synchronization issues.